In the field of underground continuous coal mining, it is well known to have a machine, known as a miner, enter a coal seam, cut the coal free, and discharge the loose coal onto a bridge conveyor. In this regard, in a typical system that utilizes a mobilized bridge carrier (MBC) the miner cuts the coal and conveys the coal to the bridge, which is attached on a pin disposed at the end of the miner's conveyor and has a catch pan beneath the dump end of the miner's conveyor. The bridge then conveys the mined coal to the dump end of the bridge where it is discharged into a hopper type dolly running along the top of the receiving conveyor, or boom, of the MBC. A conveyor on the MBC conveys the mined coal to the discharge boom which discharges the mined coal onto the receiving end of the next bridge. This sequence is repeated until the mined coal reaches a portable belt conveyor structure. The portable belt conveyor conveys the mined coal to the main belt line, which in turn conveys the mined coal to the opening of the mine. A typical coal mining operation uses a series of four bridge conveyors and three MBC units. This system permits non-stop haulage of the material from the face of the mine where it is cut to the outside of the mine to be hauled away from the mine.
Those skilled in the art will appreciate that coal seams present various heights. Thus, it is well known in the art to have both normal height bridges and bridge carriers for seams in excess of fifty inches in height as well as low profile bridges and bridge carriers for coal seams known as "low veins" that are typically between 30" and 50" in height. Bridges and bridge carriers also typically have standard widths. In this regard, certain bridge carriers have a 30" wide belt while other bridges have a 36" wide belt. Those skilled in the art appreciate that a 36" wide belt will transport a greater volume of mined coal per unit of time than will a 30" wide belt. However, presently available low vein MBC systems only have a belt width of 30 inches. This width limits the rate at which coal may hauled out of the mine. A miner can cut coal at rate faster than the haulage system can remove it. Accordingly, the miner unit cuts some coal and then remains idle until the haulage system catches up resulting in down time for the miner. This down time decreases the mines production, in terms of volume of coal extracted per a given unit of time, and results in inefficient usage of the miner. This inefficiency is exacerbated by the relatively high cost of the miner unit.
And, those skilled in the art will recognize that present construction methods do not give the booms of the MBC sufficient strength and rigidity to support the increased coal weight on the booms of the MBC that results from an increased belt width.
Known art in the field of mining equipment includes the devices disclosed in the following U.S. Patents:
______________________________________ U.S. Pat. No. Inventor(s) Issue Date ______________________________________ 4,183,585 Brennan Jan. 15, 1980 5,156,497 Gaskins Nov. 25, 1991 5,285,866 Ackroyd Feb. 15, 1994 5,341,920 Riffe Aug. 30, 1994 5,312,206 Gaskins May 17, 1994 5,584,611 Clonch Dec. 17, 1996 5,664,932 Clonch et al. Sep. 9, 1997 ______________________________________
What has heretofore been missing from the art is a low profile mobilized bridge carrier having a wide belt for greater haulage capacity than presently available systems.
Therefore, it is an object of the present invention to provide a low profile mobilized bridge carrier having a wide belt for greater haulage capacity than presently available systems.
It is another object of the present invention to provide a low profile mobilized bridge carrier having low profile reinforced booms.
Other objects and advantages of the invention over the prior art will become apparent to those skilled in the art upon reading the detailed description together with the drawings which are described below.